With two nominations each, Carrie Underwood and Luke Bryan are tied for the most nods in the country categories at this year's American Music Awards. Taylor Swift, who was crowned Artist of the Year at the 2011 AMA's and took home a total of three awards last year, was not a repeat nominee in that top catgeory but she joins Carrie in the Favorite Female Country Artist category, along with Miranda Lambert. Luke will go up against Jason Aldean and Eric Church for Favorite Male Country Artist.

Zac Brown Band, Lady Antebellum and Rascal Flatts will compete for Favorite Country Band, Duo or Group, with Luke's Tailgates & Tanlines, Carrie's Blown Away and Lionel Richie's Tuskegee vying for Favorite Country Album. The latter album, a collection of country duets by the pop icon, also features nominees Jason and Rascal Flatts.

This year marks the awards show's 40th anniversary and for the sixth year, the winners will be determined by online voting, which starts today (Oct. 9). Voting will take place here and here. In addition to the country category, artists will be honored in pop/rock, rap/hip-hop, soul/R&B, alternative, adult contemporary, Latin, contemporary inspirational and, for the first time, electronic dance music. See the full list of the 2012 nominees here.

The 40th Anniversary American Music Awards will air Sunday, Nov. 18 at 8:00 PM ET.